Induction metal melting furnace



Sept. 9, K A. LANG INDUCTION METAL MELTING FURNACE Filed April 29, 1950 /fu 1 /M/ UN/H Paten/ted Sept. 9, 1952 INDUCTION METAL MELTING FURNACE Karl A.Lang, Glenview, Ill., assigner to Lindberg Engineering Company, Chicago; Ill., a corporation of Illinois Application April 29, 1950, Serial No. 159,0fi'7 2 Claims. l

This invention relates to metal melting furnacesand more particularly to multiple Ychamber furnaces of the submerged channel type.

In furnaces of this type it is desirable to elevate the channels at one end so that they are more readily accessible for cleaning. Preferably the channels are arranged at an acute angle to the horizontal so that a cleaning tool can be inserted into their upper ends through one of the chambers to clean the channels without requiring that'the furnace be emptied.

While this construction is desirable for cleaning, .it presents one serious vdrawback which makes `its use impractical in a furnacecf conventional duced 'by electrical windings around the channels, the metal flows in the channels and produces Va relatively violent agitation in the chambers. When sloping channels are employed opening relatively close to the top of one of the chambers a severe surface agitation or boiling of the meta1 occurs in such chamber, causing excessive oxidation and resulting in an unsatisfactory melt.

According to the present invention, I have discovered that this undesirable agitation of the metal can be reduced or eliminated by providing the channels with specially shaped flared openings. lFurther limitation of agitation and other advantages can be obtained by'forming the chamber into which the upperends of the'channels open with a sloping outer vvwall and a parallel vertically spaced inner wall defining a shoulder overhanging the channel openings. Thus it is possible in accordance with the present inventionto provide an entirely practical and operative furnace in which the channels are readily accessible forcleaning and in which surface agitation of the metal is minimized and the provision of a furnace having these desirable features constitutes the principal object of the present invention.

Another specific object is to provide a furnace of the submerged channel type in which the channels are provided with openings flaring toward each other to minimize agitation of the molten metal.

Still another object is to provide a multiple chamber furnace in which one of the chambers has a sloping outer wall and a parallel inner Wall dening a shoulder overhanging the channel openings. This construction assists in reducing agitation of the metal and facilitates loading the furnace without unduly increasing the exposed area of molten metal.

The above and other objects and advantages of the invention will be more rreadily -apparent from the following description whenread in connection with the accompanying drawing, in which:

Figure l is a horizontal section through a furnace embodying the invention on the broken line l--l of Figure 2;

Figure 2 is a vertical section on the line 2 2?. of Figure l; and

Figure 3 is a partial section on the line 3 3 of Figure 2 showing the channel openings in elevation.

rThe furnace as shown comprises a casing or housing II) which may be of metal and which is lined with heat insulating material II. The in sulating material supports a furnace body I2 which may be built up of ceramic or like material. The body is formed lwith a melting chamber I3 and a holding chamber I4 spaced horizontally and connecting by a pair of sloping cylindrical tubes or channels I5 which open into the chamber I3 at a higher level than that at which they open into the chamber I4. A magnetic core IG is arranged around the channels and is energized by alternating current windings, not shown, to induce a melting current in the metal in the channels in the usual manner for furnaces of this type.

With the furnace as so `rar described the electrical action causes a flow of metal in the tubes and produces agitation of the metal in the Vchambers near the tube openings. rSince the tubes are relatively close to the surface of the metal in chamber I3, there is a tendency to cause a severe surface agitation or boilingeifect in -this chamber. At the same time it is desirable to arrange the channels with a relatively steep .slope as shown so that a cleaning tool can be inserted easily through the chamber I3 to clean thetubes and to obtain a better melting action.

According to the present invention this surface agitation is reduced or eliminated by providing a specially flared shape at the channel openings. As shown, the channels I5 terminate at their upper ends in flared generally rectangular openings defined by top walls II substantially aligned with the tops of the channels and at most flaring only very slightly. The outer sides I8 of the openings which lie closely adjacent to the outer sides of the chamber I3 are substantially aligned with the outer sides of the channels. The openings have approximately horizontal bottoms I9 which lie at an acute angle to the tube axes and their inner or adjacent sides 2| nare sharply toward each other. Thus the from the tubes are directed toward each other and have a counteracting or cancelling effect on each other. In any event experiments with outlet openings of different shapes have shown that when either the tops or outer sides of the openings are flared or When the bottoms are flared below the horizontal or when the flare of the inner sides toward each other is omitted severe surface agitation is present resulting in unsatis- N factory operation.

According to another feature of the invention, the melting chamber I3 is forming with a sloping outer wall 22 extending at an 'acute Vangle to the vertical. At its bottom the Wall 22 joins a short vertical wall 23 in which the channel openings are formed and an inner wall 24 parallel to the wall 22 joins the vertical wall 23 just above the channel openings. The wall 24 forms a shoulder overhanging the openings and further tends to reduce surface agitation of the metal while also reducing the exposed surface.

The sloping wall 22 is very advantageous in adding metal ingots or the like. In adding metal, the cold metalpieces can be slid down the wall 22 and will enter the molten ,metal smoothly without splashing. Also the slope provides a large amount of space between the channel outlets and the outer wall of the chamber I3 for insertion of acleaning tool into the channels and manipulation vof the tool in claiming the tubes. l Y

In relatively `deep furnaces having a relatively Wide -holding chamber I4 the channel openings in the holding chamber are unimportant. However, in many furnaces the holding chamber is narrow or fairly shallow or both and agitation of the metal inthe holding chamber may become severe. In these furnaces the openings in the holding chamber Aare preferably formed in the same Wayas those in the melting chamber with bottom surfaces 25 and outer side surfaces 25a parallel to the channels, horizontal top surfaces 2B, and inner side surfaces 27 flaring to- Ward each other like the surfaces 2|. f This construction eliminates or minimizes the agitation in the holding chamber.

While one embodiment of the invention had been shown and described in detail it will be understood that this is illustrative only and' is not 4 to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A metal melting furnace comprising a pair of horizontally spaced chambers, a plurality of channels connecting the chambers and lying at an acute angle to the horizontal to open into the chambers at different levels, the upper ends of the channels terminating in openings which are substantially fiared in a horizontal plane toward each other and having their upper and outer edges lying insubstantially straight lines continuous with the upper and outer boundaries respectively ofthe channels and electrical means mounted adjacent'to the channels to induce a flow of electric current through the metal therein and in the chambers.

2. A metal melting furnace comprising a pair of horizontally spaced chambers, one of the chambers being defined by an outer Wall lying at an acute angle to the vertical, a vertical wall joining the lower end of the outer Wall, and an inner wall parallel to the outer wall and joining the top of the vertical wall, and channels connecting the chambers and opening into said one of the chambers adjacent the top of the vertical wall, the channels sloping downward at an acute angle from said opening toward the other chamber, the inner wall defining a sloping shoulder overhanging the channel openings, and means defining outlets for the upper ends of the channels which are substantially flared in a horizontal plane toward each other and having their top and outer side surfaces lying in substantially straight lines continuous with the upper and outer boundaries respectively of the channels and electrical means mounted adjacent to the channels to induce avflow of electric current through the metal therein and in the chambers.

' KARL A. LANG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Lillienberg Feb. 6, 1951 

